Loading docks and other buildings that require relatively large doorways typically utilize sectional doors that retract upwardly to open. Sectional doors typically include a plurality of rectangular panels connected together by hinges along upper and lower edges. The door panels typically carry rollers or other guide members that extend outwardly from the side edges to engage guide channels in door tracks that extend vertically along each side of the door opening. Seals (e.g., bulb seals) are often provided along the side edges of the door panels to seal the gaps between the door and the door tracks. Some door tracks (e.g., tracks for “overhead” doors) extend horizontally into the building above the door so that the door is stored in this position when fully opened. Other door tracks extend vertically, or at least generally vertically, along the wall above the door opening so that the door is stored in a generally vertical position when fully opened.
Many vertically-opening doors are manually opened, while others include powered or automatic door opening systems. Moreover, many vertically-opening door systems include a counterbalance assembly positioned above the door to assist opening. Conventional counterbalance assemblies include two cable drums positioned on opposite ends of a shaft. Each drum carries a cable that is wound around the drum at one end and attached to an upper corner of the door at the other end. The shaft is typically coupled to a one or more torsion springs that bias the drums in a direction that puts tension on the cables to assist raising the door.
Vertically-opening doors should be properly aligned and positioned relative to the door opening. Otherwise, the gaps between the side edges of the door panels and the door tracks may be uneven or excessive. For doors having seals along the side edges, this misalignment can result in gaps between the guide tracks and the seals which may in turn lead to a number of undesirable consequences, including loss of heating or cooling energy, contamination, etc.
Conventional methods for leveling vertically-opening doors typically include enlisting the aid of a specialist to adjust the relative lengths of the two counterbalance assembly cables. This usually involves repositioning one or both of the cable drums on the shaft to take up or let out more cable as necessary to adjust the door angle. This approach has a number of shortcomings, not the least of which is the need to engage a specialist, which can be time-consuming and costly. Moreover, it may be difficult to fine tune cable length by rotating the corresponding cable drum. Accordingly, it would be advantageous to provide a system and method that would enable a door operator to easily and quickly adjust the orientation and/or position of a vertically-opening door without the need for special tools or training.